- Update to version 20201021.adb6953:
* Prepare for multiple python3 flavors
- Remove multiple_flavors.patch as it is included in the upstream
tarball.

- Update to version 20201016.5d22545:
* fix whitespace after escape in compileall macro

- Update to version 20201016.db09189:
* Delete pycache files before compilealll
* Update macros/010-common-defs
* Reword compileall
* mention pyproject.toml and link to PEP517 and PEP518
* add description for pyunittest macro
* add description for python_compileall macro
* add description for pyproject macros
* add python_compileall macro and use it in pyproject_install
* disable pip version check: no connection to pypi.org

- Update multiple_flavors.patch to generate correct names of the
python binary.

- %__#FLAVOR# should be defined as
/usr/bin/python%{#FLAVOR#_version} not just /usr/bin/#FLAVOR#

- Add patch multiple_flavors.patch which makes compile_macros.sh
generate alternative flavours as well.